Hybrid vehicle and control method therefor

ABSTRACT

A hybrid vehicle includes a multi-cylinder engine, an exhaust gas control apparatus including a catalyst for removing exhaust gas from the multi-cylinder engine, an electric motor, and a control device configured to execute catalyst temperature increase control for stopping fuel supply to at least one cylinder and making an air-fuel ratio in each of remaining cylinders rich in a case where a temperature increase of a catalyst is requested during a load operation of the multi-cylinder engine, execute control such that an electric motor supplements insufficient drive power due to the execution of the catalyst temperature increase control, and change the air-fuel ratio in at least one of the remaining cylinders to a lean side after a temperature of the exhaust gas control apparatus becomes equal to or higher than a determination threshold value during the execution of the catalyst temperature increase control.

INCORPORATION BY REFERENCE

The disclosure of Japanese Patent Application No. 2019-186128 filed onOct. 9, 2019 including the specification, drawings and abstract isincorporated herein by reference in its entirety.

BACKGROUND 1. Technical Field

The present disclosure relates to a hybrid vehicle including amulti-cylinder engine, an exhaust gas control apparatus including acatalyst for removing exhaust gas from the multi-cylinder engine, and anelectric motor, and a control method therefor.

2. Description of Related Art

In the related art, a control device that, in a case where an SOxpoisoning amount of a catalyst device disposed in an exhaust passage ofan internal combustion engine exceeds a predetermined value, executescatalyst temperature increase control (dither control) for setting anair-fuel ratio of a part of cylinders (rich cylinders) to rich andsetting an air-fuel ratio of a part of cylinders (lean cylinders) tolean is known (for example, see Japanese Unexamined Patent ApplicationPublication No. 2004-218541 (JP 2004-218541 A)). The control devicemakes a degree of richness of a rich cylinder and a degree of leannessof a lean cylinder different between an initial stage of the start ofthe temperature increase control and a later stage. The control devicechanges the degree of richness and the degree of leanness over time fromthe start of the temperature increase control such that the degree ofrichness and the degree of leanness at the initial stage of the start ofthe temperature increase control become small. With this, it is possibleto increase the temperature of the catalyst device while suppressing theoccurrence of misfire in the lean cylinder.

In related art, a control device that executes, as catalyst temperatureincrease control for warming up a catalyst device that removes exhaustgas from an internal combustion engine, sequentially executes ignitiontiming retard control, fuel cut and rich control and lean and richcontrol (dither control) is known (for example, see Japanese UnexaminedPatent Application Publication No. 2011-069281 (JP 2011-069281 A)). Theignition timing retard control is control for retarding an ignitiontiming and warming up the catalyst device using high-temperature exhaustgas. The fuel cut and rich control is control for making a cylinder, towhich fuel injection is stopped while an intake valve and an exhaustvalve are operated, and a cylinder, to which fuel is injected such thatan air-fuel ratio is made rich, alternately appear. The fuel cut andrich control is executed for about three seconds in a case where atemperature of a catalyst inlet reaches a first temperature under theignition timing retard control. With this, oxygen and unburned gas aresent to the catalyst device, and the catalyst device is warmed up byreaction heat of an oxidation reaction. Then, the lean and rich controlis executed until a temperature of the catalyst outlet reaches thesecond temperature after the temperature of the catalyst inlet reaches asecond temperature higher than the first temperature.

In the related art, as a control device of a hybrid vehicle including aninternal combustion engine and an electric motor, a control device isknown that stops fuel supply to each cylinder of the internal combustionengine in a case where requested power to the internal combustion enginebecomes less than a threshold value, and executes control such that anelectric motor outputs torque based on requested torque and correctiontorque at a timing when a correction start time has elapsed from a fuelcut start timing. The control device predicts the shortest time and thelongest time from the fuel cut start timing until torque shock due tofuel cut occurs based on a rotation speed and the number of cylinders ofthe internal combustion engine, and sets a time between the shortesttime and the longest time as the correction start time. The correctiontorque is determined to cancel torque shock that is applied to a driveshaft.

SUMMARY

However, even though the catalyst temperature increase control of therelated art described above is executed, in a case where anenvironmental temperature is low or in a case where a requestedtemperature to the catalyst temperature increase control is high,sufficient air, that is, oxygen may not be sent to the catalyst deviceand the catalyst device may not be sufficiently increased intemperature. The amount of oxygen requested for regeneration of thecatalyst or a particulate filter of the exhaust gas control apparatus ishardly introduced into the exhaust gas control apparatus under thecatalyst temperature increase control of the related art. On the otherhand, in a case where the catalyst temperature increase control isexecuted during a load operation of the internal combustion engine,there is a need to suppress deterioration of drivability of a vehicle inwhich the internal combustion engine is mounted.

Accordingly, the present disclosure provides a technique forsufficiently and quickly increasing a temperature of a catalyst of anexhaust gas control apparatus and supplying a sufficient amount ofoxygen to the exhaust gas control apparatus while suppressingdeterioration of drivability of a vehicle during a load operation of amulti-cylinder engine.

A first aspect of the present disclosure relates to a hybrid vehicle.The hybrid vehicle includes a multi-cylinder engine, an exhaust gascontrol apparatus, an electric motor, and an electric power storagedevice. The exhaust gas control apparatus includes a catalyst. Thecatalyst is configured to remove exhaust gas from the multi-cylinderengine. The electric power storage device is configured to exchangeelectric power with the electric motor. At least one of themulti-cylinder engine and the electric motor outputs drive power towheels. The hybrid vehicle further includes a control device. Thecontrol device is configured to execute catalyst temperature increasecontrol for stopping fuel supply to at least one cylinder and making anair-fuel ratio in each of remaining cylinders other than the at leastone cylinder rich in a case where a temperature increase of the catalystis requested during a load operation of the multi-cylinder engine,execute control such that the electric motor supplements insufficientdrive power due to the execution of the catalyst temperature increasecontrol, and change the air-fuel ratio in at least one of the remainingcylinders to a lean side after a temperature of the exhaust gas controlapparatus becomes equal to or higher than a determination thresholdvalue determined in advance during the execution of the catalysttemperature increase control.

A second aspect of the present disclosure relates to a control methodfor a hybrid vehicle. The hybrid vehicle includes a multi-cylinderengine, an exhaust gas control apparatus, an electric motor, and anelectric power storage device. The exhaust gas control apparatusincludes a catalyst. The catalyst is configured to remove exhaust gasfrom the multi-cylinder engine. The electric power storage device isconfigured to exchange electric power with the electric motor. At leastone of the multi-cylinder engine and the electric motor outputs drivepower to wheels. The control method includes executing catalysttemperature increase control for stopping fuel supply to at least onecylinder and making an air-fuel ratio in each of remaining cylindersother than the at least one cylinder rich in a case where a temperatureincrease of the catalyst is requested during a load operation of themulti-cylinder engine, executing control such that the electric motorsupplements insufficient drive power due to the execution of thecatalyst temperature increase control, and changing the air-fuel ratioin at least one of the remaining cylinders to a lean side after atemperature of the exhaust gas control apparatus becomes equal to orhigher than a determination threshold value determined in advance duringthe execution of the catalyst temperature increase control.

BRIEF DESCRIPTION OF THE DRAWINGS

Features, advantages, and technical and industrial significance ofexemplary embodiments of the present disclosure will be described belowwith reference to the accompanying drawings, in which like numeralsdenote like elements, and wherein:

FIG. 1 is a schematic configuration diagram showing a hybrid vehicle ofthe present disclosure;

FIG. 2 is a schematic configuration diagram showing a multi-cylinderengine included in the hybrid vehicle of FIG. 1 ;

FIG. 3 is a flowchart illustrating a particulate filter regenerationneed determination routine that is executed in the hybrid vehicle ofFIG. 1 ;

FIG. 4 is a flowchart illustrating a catalyst temperature increasecontrol routine that is executed in the hybrid vehicle of FIG. 1 ;

FIG. 5 is a flowchart illustrating the catalyst temperature increasecontrol routine that is executed in the hybrid vehicle of FIG. 1 ;

FIGS. 6A and 6B is a flowchart illustrating drive control routine thatis executed in the hybrid vehicle of FIG. 1 ;

FIG. 7 is an explanatory view showing the relationship between torqueoutput from a multi-cylinder engine and an ignition timing;

FIG. 8 is a time chart showing an operation state of the multi-cylinderengine or change in temperature of a particulate filter while theroutines shown in FIGS. 4 to 6A and 6B are executed;

FIG. 9 is a schematic configuration diagram showing another hybridvehicle of the present disclosure;

FIG. 10 is a schematic configuration diagram showing still anotherhybrid vehicle of the present disclosure;

FIG. 11 is a schematic configuration diagram showing still anotherhybrid vehicle of the present disclosure; and

FIG. 12 is a schematic configuration diagram showing still anotherhybrid vehicle of the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

Next, a mode for carrying out the present disclosure will be describedreferring to the drawings.

FIG. 1 is a schematic configuration diagram showing a hybrid vehicle 1of the present disclosure. The hybrid vehicle 1 shown in the drawingincludes multi-cylinder engine (hereinafter, simply referred to as an“engine”) 10 including a plurality (in the embodiment, for example,four) of cylinders (combustion chamber) 11, a single-pinion typeplanetary gear 30, motor generators MG1, MG2, both of which aresynchronous motor generators (three-phase alternating-current electricmotors), an electric power storage device (battery) 40, an electricpower control unit (hereinafter, referred to as “PCU”) 50 that isconnected to the electric power storage device 40 and drives the motorgenerators MG1, MG2, an electronically controlled hydraulic brakingdevice 60 that is able to provide frictional braking force to wheels W,and a hybrid electronic control unit (hereinafter, referred to as“HVECU”) 70 that controls the entire vehicle.

The engine 10 is an in-line gasoline engine (internal combustion engine)that converts reciprocating motion of pistons (not shown) accompanied bycombustion of an air-fuel mixture of hydrocarbon based fuel and air in aplurality of cylinders 11 into rotational motion of a crankshaft (outputshaft) 12. As shown in FIG. 2 , the engine 10 includes an intake pipe13, an intake manifold 13 m, a throttle valve 14, a plurality of intakevalves and a plurality of exhaust valves (not shown), a plurality ofport injection valves 15 p, a plurality of in-cylinder injection valves15 d, a plurality of ignition plugs 16, an exhaust manifold 17 m, and anexhaust pipe 17. The throttle valve 14 is an electronically controlledthrottle valve that is able to change a passage area in the intake pipe13. The intake manifold 13 m is connected to the intake pipe 13 and anintake port of each of the cylinders 11. Each of the port injectionvalves 15 p injects fuel to the corresponding to intake port, and eachof the in-cylinder injection valves 15 d injects fuel directly to thecorresponding cylinder 11. The exhaust manifold 17 m is connected to anexhaust port of each of the cylinders 11 and the exhaust pipe 17.

The engine 10 includes a low-pressure delivery pipe DL connected to afeed pump (low-pressure pump) Pf through a low-pressure fuel supply pipeLL and a high-pressure delivery pipe DH connected to a supply pump(high-pressure pump) Ps through a high-pressure fuel supply pipe LH. Afuel inlet of each of the port injection valves 15 p is connected to thelow-pressure delivery pipe DL, and a fuel inlet of each of thein-cylinder injection valves 15 d is connected to the high-pressuredelivery pipe DH. The feed pump Pf is an electric pump including a motorthat is driven with electric power from an accessory battery (notshown). Fuel from the feed pump Pf is stored in the low-pressuredelivery pipe DL and is supplied from the low-pressure delivery pipe DLto the respective port injection valves 15 p. The supply pump Ps is apiston pump (mechanical pump) that is driven by, for example, the engine10. High-pressure fuel from the supply pump Ps is stored in thehigh-pressure delivery pipe DH and is supplied from the high-pressuredelivery pipe DH to the respective in-cylinder injection valves 15 d.

As shown in FIG. 2 , the engine 10 includes an evaporative fueltreatment device 110 that introduces evaporative fuel generated in afuel tank Tk, which stores fuel, into the intake manifold 13 m. Theevaporative fuel treatment device 110 includes a canister 111 that hasan adsorbent (activated carbon) adsorbing evaporative fuel in the fueltank Tk, a vapor passage Lv that connects the fuel tank Tk and thecanister 111, a purge passage Lp that connects the canister 111 and theintake manifold 13 m, and a purge valve (vacuum switching valve) Vsvthat is provided in the purge passage Lp. In the embodiment, the purgevalve Vsv is a control valve that is able to regulate a valve openingdegree.

The engine 10 includes, as an exhaust gas control apparatus, an upstreamcontrol apparatus 18 and a downstream control apparatus 19 incorporatedin the exhaust pipe 17. The upstream control apparatus 18 includes anNOx storage type exhaust gas removing catalyst (three-way catalyst) 180that removes harmful components, such as carbon monoxide (CO), HC, andNOx, in exhaust gas from the respective cylinders 11 of the engine 10.The downstream control apparatus 19 includes a particulate filter (GPF)190 that is disposed downstream of the upstream control apparatus 18 andtraps particulate matters (fine particles) in exhaust gas. In theembodiment, the particulate filter 190 carries an NOx storage typeexhaust gas removing catalyst (three-way catalyst).

The engine 10 as described above is controlled by an engine electroniccontrol unit (hereinafter, referred to as “engine ECU”) 100. The engineECU 100 includes a microcomputer having a CPU, a ROM, a RAM, aninput/output interface, and the like (not shown), various drivecircuits, various logic ICs, and the like, and executes intake airamount control, fuel injection control, and ignition timing control ofthe engine 10, purge control for controlling a purge amount ofevaporative fuel in the evaporative fuel treatment device 110 (purgevalve Vsv), and the like. The engine ECU 100 acquires detection valuesof a crank angle sensor 90, a coolant temperature sensor 91, an airflowmeter 92, an intake pressure sensor (not shown), a throttle valveposition sensor (not shown), an upstream air-fuel ratio sensor 95, adownstream air-fuel ratio sensor 96, a differential pressure sensor 97,an upstream catalyst temperature sensor 98, a downstream catalysttemperature sensor 99, and the like through an input port (not shown).

The crank angle sensor 90 detects a rotation position (crank position)of the crankshaft 12. The coolant temperature sensor 91 detects acoolant temperature Tw of the engine 10. The air flowmeter 92 detects anintake air amount GA of the engine 10. The intake pressure sensordetects pressure in the intake pipe 13, that is, intake pressure. Thethrottle valve position sensor detects a valve body position (throttleposition) of the throttle valve 14. The upstream air-fuel ratio sensor95 detects an upstream air-fuel ratio AFf that is an air-fuel ratio ofexhaust gas flowing into the upstream control apparatus 18. Thedownstream air-fuel ratio sensor 96 detects a downstream air-fuel ratioAFr that is an air-fuel ratio of exhaust gas flowing into the downstreamcontrol apparatus 19. The differential pressure sensor 97 detectsdifferential pressure ΔP of exhaust gas between an upstream side and adownstream side of the downstream control apparatus 19, that is, theparticulate filter 190. The upstream catalyst temperature sensor 98detects a temperature (catalyst temperature) Tct of the upstream controlapparatus 18, that is, the exhaust gas removing catalyst 180. Thedownstream catalyst temperature sensor 99 detects a temperature(catalyst temperature) Tpf of the downstream control apparatus 19, thatis, the particulate filter 190.

The engine ECU 100 calculates a rotation speed Ne of the engine 10(crankshaft 12) based on the crank position from the crank angle sensor90. The engine ECU 100 calculates (estimates) a deposition amount Dpm ofthe particulate matters in the particulate filter 190 of the downstreamcontrol apparatus 19 at each predetermined time using either of anoperation history method according to an operation state or the like ofthe engine 10 or a differential pressure method. In a case where thedifferential pressure method is used, the engine ECU 100 calculates thedeposition amount Dpm based on the differential pressure ΔP detected bythe differential pressure sensor 97, that is, pressure loss in theparticulate filter 190 due to deposition of the particulate matters. Ina case where the operation history method is used, the engine ECU 100calculates the deposition amount Dpm (present value) by adding anestimated increase amount (positive value) or an estimated decreaseamount (negative value) of particulate matters according to theoperation state of the engine 10 to a previous value of the depositionamount Dpm. The estimated increase amount of the particulate matters iscalculated, for example, as a product of an estimated emission amount ofparticulate matters calculated from the rotation speed Ne of the engine10, a load factor, and the coolant temperature Tw, an emission factor,and trapping efficiency of the particulate filter 190. The estimateddecrease amount of the particulate matters is calculated, for example,as a product of an amount of combustion of particulate matterscalculated from the previous value of the deposition amount Dpm, aninflow air amount, and the temperature Tpf of the particulate filter190, and a correction coefficient.

The engine 10 may be a diesel engine including a diesel particulatefilter (DPF) or may be an LPG engine. The temperature Tct or Tpf of theexhaust gas removing catalyst 180 or the particulate filter 190 may beestimated based on the intake air amount GA, the rotation speed Ne, atemperature of exhaust gas, the upstream air-fuel ratio AFf, thedownstream air-fuel ratio AFr, and the like.

The planetary gear 30 is a differential rotation mechanism including asun gear (first element) 31, a ring gear (second element) 32, and aplanetary carrier (third element) 34 that rotatably supports a pluralityof pinion gears 33. As shown in FIG. 1 , a rotor of the motor generatorMG1 is coupled to the sun gear 31, and the crankshaft 12 of the engine10 is connected to the planetary carrier 34 through a damper mechanism24. The ring gear 32 is integrated with a counter drive gear 35 as anoutput member, and both gears rotate coaxially and integrally.

The counter drive gear 35 is coupled to right and left wheels (drivewheels) W through a counter driven gear 36 that meshes with the counterdrive gear 35, a final drive gear (drive pinion gear) 37 that rotatesintegrally with the counter driven gear 36, a final driven gear(differential ring gear) 39 r that meshes with the final drive gear 37,a differential gear 39, and a drive shaft DS. With this, the planetarygear 30, a gear train of the counter drive gear 35 to the final drivengear 39 r, and the differential gear 39 constitute a transaxle 20 thattransmits a part of output torque of the engine 10 as a power generationsource to the wheels W and connects the engine 10 and the motorgenerator MG1 to each other.

A drive gear 38 is fixed to a rotor of the motor generator MG2. Thedrive gear 38 has the number of teeth smaller than the counter drivengear 36 and meshes with the counter driven gear 36. With this, the motorgenerator MG2 is connected to the right and left wheels W through thedrive gear 38, the counter driven gear 36, the final drive gear 37, thefinal driven gear 39 r, the differential gear 39, and the drive shaftDS.

The motor generator MG1 (second electric motor) mostly operates as apower generator that converts at least a part of power from the engine10 in a load operation. The motor generator MG2 mostly operates as anelectric motor that is driven with at least one of electric power fromthe electric power storage device 40 and electric power from the motorgenerator MG1 to generate drive torque in the drive shaft DS. That is,in the hybrid vehicle 1, the motor generator MG2 as a power generationsource functions as a power generation device that outputs drive torque(drive power) to the wheels W attached to the drive shaft DS along withthe engine 10. The motor generator MG2 outputs regenerative brakingtorque at the time of braking of the hybrid vehicle 1. The motorgenerators MG1, MG2 are able to exchange electric power with theelectric power storage device 40 through the PCU 50 or exchange electricpower with each other through the PCU 50.

The electric power storage device 40 is, for example, a lithium-ionsecondary battery or a nickel-hydrogen secondary battery. The electricpower storage device 40 is managed by a power supply managementelectronic control unit (hereinafter, referred to as “power supplymanagement ECU”) 45 that includes a microcomputer having a CPU, a ROM, aRAM, an input/output interface, and the like (not shown). The powersupply management ECU 45 derives an SOC (charging rate), allowablecharging electric power Win, allowable discharging electric power Wout,and the like of the electric power storage device 40 based on aninter-terminal voltage VB from a voltage sensor of the electric powerstorage device 40, a charging and discharging current IB from a currentsensor, a battery temperature Tb from a temperature sensor 47 (see FIG.1 ), and the like.

The PCU 50 includes a first inverter 51 that drives the motor generatorMG1, a second inverter 52 that drives the motor generator MG2, a boostconverter (voltage conversion module) 53 that boosts electric power fromthe electric power storage device 40 and deboosts electric power fromthe motor generators MG1, MG2 side. The PCU 50 is controlled by a motorelectronic control unit (hereinafter, referred to as “MGECU”) 55 thatincludes a microcomputer having a CPU, a ROM, a RAM, an input/outputinterface, and the like (not shown), various drive circuits, variouslogic ICs, and the like. The MGECU 55 acquires a command signal from theHVECU 70, a voltage before boosting and a voltage after boosting of theboost converter 53, detection values of a resolver (not shown) thatdetects rotation positions of the rotors of the motor generators MG1,MG2, phase currents that are applied to the motor generators MG1, MG2,and the like. The MGECU 55 executes switching control of the first andsecond inverters 51, 52 or the boost converter 53 based on the signalsand the like. The MGECU 55 calculates rotation speed Nm1, Nm2 of therotors of the motor generators MG1, MG2 based on the detection values ofthe resolver.

The hydraulic braking device 60 includes a master cylinder, a pluralityof brake pads that sandwiches brake discs attached to the wheels W toprovide braking torque (frictional braking torque) to the correspondingwheels, a plurality of wheel cylinders (all not shown) that drives thecorresponding brake pads, a hydraulic brake actuator 61 that supplieshydraulic pressure to the respective wheel cylinders, and a brakeelectronic control unit (hereinafter, referred to as “brake ECU”) 65that controls the brake actuator 61, and the like. The brake ECU 65includes a microcomputer having a CPU, a ROM, a RAM, an input/outputinterface, and the like (not shown). The brake ECU 65 acquires a commandsignal from the HVECU 70, a brake pedal stroke BS (a depression amountof a brake pedal 64) detected by a brake pedal stroke sensor 63, avehicle speed V detected by a vehicle speed sensor (not shown), and thelike. The brake ECU 65 controls the brake actuator 61 based on thesignals and the like.

The HVECU 70 includes a microcomputer having a CPU, a ROM, a RAM, aninput/output interface, and the like (not shown), various drivecircuits, various logic ICs, and the like. The HVECU 70 exchangesinformation (communication frames) with the ECUs 100, 45, 55, 65 througha public communication line (multiplex communication bus) that is a CANbus including two communication lines (wire harness) of Lo and Hi. TheHVECU 70 is connected individually to each of the ECUs 100, 45, 55, 65through a dedicated communication line (local communication bus) that isa CAN bus including two communication lines (wire harness) of Lo and Hi.The HVECU 70 exchanges information (communication frames) individuallywith each of the ECUs 100, 45, 55, 65 through the correspondingdedicated communication line. The HVECU 70 acquires a signal from astart switch (not shown) for instructing a system start of the hybridvehicle 1, a shift position SP of a shift lever 82 detected by a shiftposition sensor 81, an accelerator operation amount Acc (a depressionamount of an accelerator pedal 84) detected by an accelerator pedalposition sensor 83, the vehicle speed V detected by the vehicle speedsensor (not shown), the crank position from the crank angle sensor 90 ofthe engine 10, and the like. The HVECU 70 acquires the SOC (chargingrate), the allowable charging electric power Win, and the allowabledischarging electric power Wout of the electric power storage device 40from the power supply management ECU 45, the rotation speed Nm1, Nm2 ofthe motor generators MG1, MG2 from the MGECU 55, and the like.

The HVECU 70 derives requested torque Tr* (including requested brakingtorque) to be output to the drive shaft DS corresponding to theaccelerator operation amount Acc and the vehicle speed V from arequested torque setting map (not shown) at the time of traveling of thehybrid vehicle 1. The HVECU 70 sets requested traveling power Pd*(=Tr*×Nds) requested for traveling of the hybrid vehicle 1 based on therequested torque Tr* or a rotation speed Nds of the drive shaft DS. TheHVECU 70 determines whether or not to make the engine 10 perform theload operation based on the requested torque Tr* or the requestedtraveling power Pd*, separately set target charging and dischargingelectric power Pb* or the allowable discharging electric power Wout ofthe electric power storage device 40, or the like.

In a case where the engine 10 should be made to perform the loadoperation, the HVECU 70 sets requested power Pe*(=Pd*−Pb*+Loss) to theengine 10 based on the requested traveling power Pd*, the targetcharging and discharging electric power Pb*, or the like. The HVECU 70sets a target rotation speed Ne* of the engine 10 according to therequested power Pe* such that the engine 10 is efficiently operated andfalls below a lower limit rotation speed Nelim according to a drivingstate or the like of the hybrid vehicle 1. The HVECU 70 sets torquecommands Tm1*, Tm2* to the motor generators MG1, MG2 according to therequested torque Tr*, the target rotation speed Ne*, or the like withina range of the allowable charging electric power Win and the allowabledischarging electric power Wout of the electric power storage device 40.On the other hand, in a case where the operation of the engine 10 shouldbe stopped, the HVECU 70 set the requested power Pe*, the targetrotation speed Ne*, and the torque command Tm1* to zero. The HVECU 70sets the torque command Tm2* within the range of the allowable chargingelectric power Win and the allowable discharging electric power Wout ofthe electric power storage device 40 such that torque according to therequested torque Tr* is output from the motor generator MG2 to the driveshaft DS.

Then, the HVECU 70 transmits the requested power Pe* and the targetrotation speed Ne* to the engine ECU 100, and transmits the torquecommands Tm1*, Tm2* to the MGECU 55. The engine ECU 100 executes theintake air amount control, the fuel injection control, the ignitiontiming control, and the like based on the requested power Pe* and thetarget rotation speed Ne*. In the embodiment, the engine ECU 100basically executes the fuel injection control such that an air-fuelratio in each of the cylinders 11 of the engine 10 becomes astoichiometric air-fuel ratio (=14.6 to 14.7). In a case where a load(requested power Pe*) of the engine 10 is equal to or less than apredetermined value, fuel is injected from the respective port injectionvalves 15 p, and fuel injection from the respective in-cylinderinjection valves 15 d is stopped. While the load of the engine 10exceeds the predetermined value, fuel injection from the respective portinjection valves 15 p is stopped, and fuel is injected from therespective in-cylinder injection valves 15 d. In the embodiment, fuelinjection to the cylinders 11 and ignition are executed in an order(ignition order) of a first cylinder #1→a third cylinder #3→a fourthcylinder #4→a second cylinder #2.

The MGECU 55 executes the switching control of the first and secondinverters 51, 52 or the boost converter 53 based on the torque commandsTm1*, Tm2*. In a case where the engine 10 is in the load operation,control is executed such that the motor generators MG1, MG2 converts apart (at the time of charging of the electric power storage device 40)or the whole (at the time of discharging of the electric power storagedevice 40) of power output from the engine 10 along with the planetarygear 30 into torque and outputs torque to the drive shaft DS. With this,the hybrid vehicle 1 performs traveling (HV traveling) with power(directly transmitted torque) from the engine 10 and power from themotor generator MG2. In contrast, in a case where the operation of theengine 10 is stopped, the hybrid vehicle 1 executes traveling (EVtraveling) solely with power (drive torque) from the motor generatorMG2.

Here, as described above, the hybrid vehicle 1 of the embodimentincludes, as an exhaust gas control apparatus, the downstream controlapparatus 19 having the particulate filter 190. The deposition amountDpm of the particulate matters in the particulate filter 190 increaseswith an increase in traveling distance of the hybrid vehicle 1, andincreases as the environmental temperature is lower. Accordingly, in thehybrid vehicle 1, when the deposition amount Dpm of the particulatematters in the particulate filter 190 increases, there is a need to senda large amount of air, that is, oxygen to the particulate filter 190,which is sufficiently increased in temperature, and to combust theparticulate matters to regenerate the particulate filter 190. For thisreason, in the hybrid vehicle 1, when the engine 10 is in the loadoperation according to the depression amount of the accelerator pedal 84by a driver of the hybrid vehicle 1, a particulate filter regenerationneed determination routine illustrated in FIG. 3 is executed at eachpredetermined time by the engine ECU 100.

At the time of the start of the routine of FIG. 3 , the engine ECU 100acquires information needed for determination, such as the intake airamount GA or the rotation speed Ne of the engine 10, the coolanttemperature Tw, and the temperature Tpf of the particulate filter 190(Step S100). The engine ECU 100 calculates the deposition amount Dpm ofthe particulate matters in the particulate filter 190 based on physicalquantity and the like acquired in Step S100 using either of theoperation history method according to the operation state or the like ofthe engine 10 or the differential pressure method (Step S110). Next, theengine ECU 100 determines whether or not a catalyst temperature increasecontrol routine for increasing the temperature of the exhaust gasremoving catalyst 180 of the upstream control apparatus 18 and thetemperature of the particulate filter 190 of the downstream controlapparatus 19 is already executed (Step S120).

In a case where determination is made in Step S120 that the catalysttemperature increase control routine is not executed (Step S120: YES),the engine ECU 100 determines whether or not the deposition amount Dpmcalculated in Step S110 is equal to or greater than a threshold value D1(for example, a value of about 5000 mg) determined in advance (StepS130). In a case where determination is made in Step S130 that thedeposition amount Dpm is less than the threshold value D1 (Step S130:NO), the engine ECU 100 ends the routine of FIG. 3 at this point of timeonce. In a case where determination is made in Step S130 that thedeposition amount Dpm is equal to or greater than the threshold value D1(Step S130: YES), the engine ECU 100 determines whether or not thetemperature Tpf of the particulate filter 190 acquired in Step S100 islower than a temperature increase control start temperature(predetermined temperature) Tx determined in advance (Step S140). Thetemperature increase control start temperature Tx is determined inadvance according to a use environment of the hybrid vehicle 1, and inthe embodiment, is, for example, a temperature near 600° C.

In a case where determination is made in Step S140 that the temperatureTpf of the particulate filter 190 is equal to or higher than thetemperature increase control start temperature Tx (Step S140: NO), theengine ECU 100 ends the routine of FIG. 3 at this point of time once. Ina case where determination is made in Step S140 that the temperature Tpfof the particulate filter 190 is lower than the temperature increasecontrol start temperature Tx (Step S140: YES), the engine ECU 100transmits a catalyst temperature increase request signal for requestingthe execution of the catalyst temperature increase control routine tothe HVECU 70 (Step S150), and ends the routine of FIG. 3 once. In a casewhere the execution of the catalyst temperature increase control routineis permitted by the HVECU 70 after the transmission of the catalysttemperature increase request signal, the engine ECU 100 turns on acatalyst temperature increase flag and starts the catalyst temperatureincrease control routine.

On the other hand, in a case where determination is made in Step S120that the catalyst temperature increase control routine is alreadyexecuted (Step S120: NO), the engine ECU 100 determines whether or notthe deposition amount Dpm calculated in Step S110 is equal to or lessthan a threshold value D0 (for example, a value of about 3000 mg)determined to be smaller than the threshold value D1 in advance (StepS160). In a case where determination is made in Step S160 that thedeposition amount Dpm is greater than the threshold value D0 (Step S160:NO), the engine ECU 100 ends the routine of FIG. 3 at this point of timeonce. In a case where determination is made in Step S160 that thedeposition amount Dpm is equal to or less than the threshold value D0(Step S160: YES), the engine ECU 100 turns off the catalyst temperatureincrease flag and ends the catalyst temperature increase control routine(Step S170), and ends the routine of FIG. 3 .

Subsequently, the catalyst temperature increase control routine forincreasing the temperature of the exhaust gas removing catalyst 180 andthe temperature of the particulate filter 190 will be described. FIG. 4is a flowchart illustrating the catalyst temperature increase controlroutine that is executed by the engine ECU 100 at each predeterminedtime. The routine of FIG. 4 is executed until the catalyst temperatureincrease flag is turned off in Step S170 of FIG. 3 under a conditionthat the execution of the routine is permitted by the HVECU 70 while theengine 10 is in the load operation according to the depression amount ofthe accelerator pedal 84 by the driver.

At the time of the start of the routine of FIG. 4 , the engine ECU 100acquires information needed for control, such as the intake air amountGA or the rotation speed Ne of the engine 10, the coolant temperatureTw, the temperature Tpf of the particulate filter 190, the crankposition from the crank angle sensor 90, and the requested power Pe* andthe target rotation speed Ne* from the HVECU 70 (Step S200). After theprocessing of Step S200, the engine ECU 100 determines whether or not arichness flag Fr is a value 0 (Step S210). Before the start of theroutine of FIG. 4 , the richness flag Fr is set to the value 0, and in acase where determination is made in Step S210 that the richness flag Fris the value 0 (Step S6210: YES), the engine ECU 100 sets the richnessflag Fr to a value 1 (Step S220).

Next, the engine ECU 100 sets fuel injection controlled variables, suchas a fuel injection amount or a fuel injection end timing, from therespective port injection valves 15 p or the respective in-cylinderinjection valves 15 d (Step S230). In Step S230, the engine ECU 100makes the fuel injection amount to one cylinder 11 (for example, a firstcylinder #1) zero among a plurality of cylinders 11 of the engine 10. InStep S230, the engine ECU 100 increases the fuel injection amount toeach of the remaining cylinders 11 (for example, a second cylinder #2, athird cylinder #3, and a fourth cylinder #4) other than the one cylinder11 by, for example, 20% to 25% (in the embodiment, 20%) of the fuelinjection amount, which should be intrinsically supplied to the onecylinder 11 (the first cylinder #1).

After the fuel injection controlled variables are set in Step S230, theengine ECU 100 discriminates the cylinder 11, the fuel injection starttiming of which is reached, based on the crank position from the crankangle sensor 90 (Step S240). In a case where determination is madethrough the discrimination processing of Step S240 that the fuelinjection start timing of the one cylinder 11 (the first cylinder #1) isreached (Step S250: NO), the engine ECU 100 does not perform fuelinjection from the port injection valve 15 p or the in-cylinderinjection valve 15 d corresponding to the one cylinder 11, anddetermines whether or not one cycle of fuel injection, in which theengine 10 is rotated twice, is completed (Step S270). While the fuelsupply to the one cylinder 11 (the first cylinder #1) is stopped (duringfuel cut), the intake valve and the exhaust valve of the cylinder 11 areopened and closed in the same manner as in a case where fuel issupplied. In a case where determination is made through thediscrimination processing of Step S240 that the fuel injection starttiming of one of the remaining cylinders 11 (the second cylinder #2, thethird cylinder #3, or the fourth cylinder #4) is reached (Step S250:YES), the engine ECU 100 performs fuel inject from the port injectionvalve 15 p or the in-cylinder injection valve 15 d to the cylinder 11(Step S260), and determines whether or not one cycle of fuel injectionis completed (Step S270).

In a case where determination is made in Step S270 that one cycle offuel injection is not completed (Step s270: NO), the engine ECU 100repeatedly executes the processing of Steps S240 to S260. While theroutine is executed, an opening degree of the throttle valve 14 is setbased on the requested power Pe* and the target rotation speed Ne*(requested torque). Accordingly, through the processing of Steps S240 toS270, the fuel supply to the one cylinder 11 (the first cylinder #1) isstopped, and the air-fuel ratio in each of the remaining cylinders 11(the second cylinder #2, the third cylinder #3, and the fourth cylinder#4) is made rich. In the following description, the cylinder 11, towhich the fuel supply is stopped, is appropriately referred to as a“fuel cut cylinder”, and the cylinder 11, to which fuel is supplied, isappropriately referred to as a “combustion cylinder”. In a case wheredetermination is made in Step S270 that one cycle of fuel injection iscompleted (Step S270: YES), the engine ECU 100 executes the processingof Step S200 and subsequent steps again.

After the richness flag Fr is set to the value 1 in Step S220, theengine ECU 100 determines in Step S210 that the richness flag Fr is thevalue 1 (Step S210: YES). In this case, the engine ECU 100 determineswhether or not the temperature Tpf of the particulate filter 190acquired in Step S200 is lower than a regenerative temperature (firstdetermination threshold value) Ty determined in advance (Step S215). Theregenerative temperature Ty is a lower limit value of a temperature forallowing regeneration of the particulate filter 190, that is, combustionof the particulate matters or a temperature slightly higher than thelower limit value. The regenerative temperature Ty is determined inadvance according to the use environment of the hybrid vehicle 1, and inthe embodiment, is set to, for example, a temperature near 650° C. In acase where determination is made in Step S215 that the temperature Tpfof the particulate filter 190 is lower than the regenerative temperatureTy (Step S215: YES), the engine ECU 100 executes the processing of StepsS230 to S270 described above, and executes the processing of Step S200and the subsequent steps again.

In a case where determination is made in Step S215 that the temperatureTpf of the particulate filter 190 is equal to or higher than theregenerative temperature Ty (Step S215: NO), as shown in FIG. 5 , theengine ECU 100 determines whether or not a high temperature flag Ft is avalue 0 (Step S280). Before the start of the routine of FIG. 4 , thehigh temperature flag Ft is set to the value 0, and in a case wheredetermination is made in Step S280 that the high temperature flag Ft isthe value 0 (Step S280: YES), the engine ECU 100 sets the richness flagFr to the value 0 (Step S290). After the richness flag Fr is set to thevalue 0, the engine ECU 100 determines whether or not the temperatureTpf of the particulate filter 190 acquired in Step S200 is equal to orhigher than a regeneration promotion temperature (second determinationthreshold value) Tz determined in advance (Step S300). The regenerationpromotion temperature Tz is a temperature for allowing promotion ofregeneration of the particulate filter 190, that is, combustion of theparticulate matters. The regeneration promotion temperature Tz isdetermined in advance according to the use environment of the hybridvehicle 1, and in the embodiment, is set to, for example, a temperaturenear 700° C.

In a case where determination is made in Step S300 that the temperatureTpf of the particulate filter 190 is lower than the regenerationpromotion temperature Tz (Step S300: NO), the engine ECU 100 sets thefuel injection controlled variables, such as the fuel injection amountor the fuel injection end timing, from the respective port injectionvalves 15 p or the respective in-cylinder injection valves 15 d (StepS310). In Step S310, the engine ECU 100 makes the fuel injection amountto the fuel cut cylinder (the first cylinder #1) among the cylinders 11zero. In Step S310, the engine ECU 100 increases the fuel injectionamount to each of all combustion cylinders (the second cylinder #2, thethird cylinder #3, and the fourth cylinder #4) other than the fuel cutcylinder (the first cylinder #1) by, for example, 3% to 7% (in theembodiment, 5%) of the fuel injection amount, which should beintrinsically supplied to the fuel cut cylinder.

After the fuel injection controlled variables are set in Step S310, theengine ECU 100 repeatedly executes the processing of Steps S240 to S260until determination is made in Step S270 that one cycle of fuelinjection is completed. With this, the fuel supply to the one cylinder(fuel cut cylinder) 11 (the first cylinder #1) is stopped, the air-fuelratio in each of the remaining cylinders (combustion cylinders) 11 (thesecond cylinder #2, the third cylinder #3, and the fourth cylinder #4)is changed to a lean side compared to a case where the processing ofStep S230 is executed and is made slightly rich.

In a case where determination is made in Step S300 that the temperatureTpf of the particulate filter 190 is equal to or higher than theregeneration promotion temperature Tz (Step S300: YES), the engine ECU100 sets the high temperature flag Ft to the value 1 (Step S305). InStep S305, the engine ECU 100 transmits an F/C cylinder addition requestsignal for requesting addition of a fuel cut cylinder to the HVECU 70.Then, the engine ECU 100 sets the fuel injection controlled variables ofthe respective port injection valves 15 p or the respective in-cylinderinjection valves 15 d (Step S310), and repeatedly executes theprocessing of Steps S240 to S260 until determination is made in StepS270 that one cycle of fuel injection is completed.

In the embodiment, the engine ECU 100 sets the high temperature flag Ftto the value 1 in Step S305, and then, transmits the F/C cylinderaddition request signal to the HVECU 70 once in two cycles (fourrotations of the engine 10). Permission and prohibition of addition of afuel cut cylinder is determined by the HVECU 70. In a case whereaddition of a fuel cut cylinder is permitted by the HVECU 70, the engineECU 100 selects (adds), as a new fuel cut cylinder, the cylinder 11 (inthe embodiment, the fourth cylinder #4) to which fuel injection(ignition) is not executed successively with respect to the firstcylinder #1 when the catalyst temperature increase control routine isnot executed.

In a case where addition of a fuel cut cylinder is permitted by theHVECU 70, the engine ECU 100 makes the fuel injection amount to each ofthe fuel cut cylinders (the first cylinder #1 and the fourth cylinder#4) among the cylinders 11 zero in Step S310. In Step S310, the engineECU 100 increases the fuel injection amount to each of all combustioncylinders (the second cylinder #2 and the third cylinder #3) other thanthe fuel cut cylinders by, for example, 3% to 7% (in the embodiment, 5%)of the fuel injection amount, which should be intrinsically supplied toone fuel cut cylinder. In this case, after the processing of Step S310,the engine ECU 100 executes the processing of Steps S240 to S270, andexecutes the processing of Step S200 and the subsequent steps again.With this, the fuel supply to the two cylinders 11 (the first cylinder#1 and the fourth cylinder #4) is stopped, and the air-fuel ratio ineach of the remaining cylinders 11 (the second cylinder #2 and the thirdcylinder #3) is changed to a lean side compared to a case where theprocessing of Step S230 is executed and is made slightly rich.

After the high temperature flag Ft is set to the value 1 in Step S305,the engine ECU 100 determines in Step S280 that the high temperatureflag Ft is the value 1 (Step S280: NO). In this case, the engine ECU 100determines whether or not the temperature Tpf of the particulate filter190 acquired in Step S200 is lower than the temperature increase controlstart temperature Tx (Step S320). In a case where determination is madein Step S320 that the temperature Tpf of the particulate filter 190 isequal to or higher than the temperature increase control starttemperature Tx (Step S320: NO), the engine ECU 100 executes theprocessing of Steps S310 and S240 to S270, and executes the processingof Step S200 and the subsequent steps again. In contrast, in a casewhere determination is made in Step S320 that the temperature Tpf of theparticulate filter 190 is lower than the temperature increase controlstart temperature Tx (Step S320: YES), the engine ECU 100 sets the hightemperature flag Ft to the value 0 (Step S325). In Step S325, the engineECU 100 transmits an F/C cylinder reduction signal to the HVECU 70 inorder to notify of the restart of fuel supply to the previously addedfuel cut cylinder (the fourth cylinder #4).

After the processing of Step S325, the engine ECU 100 sets the richnessflag Fr to the value 1 again in Step S220 of FIG. 4 . The engine ECU 100makes the fuel injection amount to the fuel cut cylinder (first cylinder#1), to which the fuel supply is stopped continuously, zero, andincreases the fuel injection amount to each of the remaining cylinders(combustion cylinders) 11 (the second cylinder #2, the third cylinder#3, and the fourth cylinder #4) by 20% of the fuel injection amount,which should be intrinsically supplied to the one fuel cut cylinder(first cylinder #1) (Step S230). With this, through the processing ofSteps S240 to S270, the fuel supply of the one cylinder (fuel cutcylinder) 11 (the first cylinder #1) is stopped, and the air-fuel ratioin each of the remaining cylinders (combustion cylinder) 11 (the secondcylinder #2, the third cylinder #3, and the fourth cylinder #4) is maderich again.

FIGS. 6A and 6B is a flowchart illustrating a drive control routine thatis repeatedly executed by the HVECU 70 at each predetermined time inparallel with the above-described catalyst temperature increase controlroutine after the catalyst temperature increase request signal istransmitted from the engine ECU 100 in Step S150 of FIG. 3 .

At the time of the start of the routine of FIGS. 6A and 6B, the HVECU 70acquires information needed for control, such as the acceleratoroperation amount Acc, the vehicle speed V, the crank position from thecrank angle sensor 90, the rotation speed Nm1, Nm2 of the motorgenerators MG1, MG2, the SOC, the target charging and dischargingelectric power Pb*, the allowable charging electric power Win, and theallowable discharging electric power Wout of the electric power storagedevice 40, the presence or absence of reception of the F/C cylinderaddition request signal and the F/C cylinder reduction signal from theengine ECU 100, and the value of the richness flag Fr from the engineECU 100 (Step S400). Next, the HVECU 70 sets the requested torque Tr*based on the accelerator operation amount Acc and the vehicle speed V,and sets the requested power Pe* to the engine 10 based on the requestedtorque Tr* (requested traveling power Pd*), the target charging anddischarging electric power Pb* of the electric power storage device 40,or the like (Step S410).

The HVECU 70 determines whether or not the catalyst temperature increasecontrol routine of FIGS. 4 and 5 is started by the engine ECU 100 (StepS420). In a case where determination is made in Step S420 that thecatalyst temperature increase control routine is not started by theengine ECU 100 (Step S420: YES), the HVECU 70 sets a value Nerefdetermined in advance as the lower limit rotation speed Nelim that is alower limit value of the rotation speed of the engine 10 (Step S430).The value Neref is a value that is greater by about 400 to 500 rpm thanthe lower limit value of the rotation speed of the engine 10 when thecatalyst temperature increase control routine is not executed. Theprocessing of Step S430 is skipped after the catalyst temperatureincrease control routine is started by the engine ECU 100.

After the processing of Step S420 or S430, the HVECU 70 derives arotation speed for efficiently operating the engine 10 corresponding tothe requested power Pe* from a map (not shown) and sets a greater valuebetween the derived rotation speed and the lower limit rotation speedNelim as the target rotation speed Ne* of the engine 10 (Step S440). InStep S440, the HVECU 70 sets a value obtained by dividing the requestedpower Pe* by the target rotation speed Ne* as target torque Te* of theengine 10. The HVECU 70 sets the torque command Tm1* to the motorgenerator MG1 according to the target torque Te* and the target rotationspeed Ne* and the torque command Tm2* to the motor generator MG2according to the requested torque Tr* and the torque command Tm1* withinthe range of the allowable charging electric power Win and the allowabledischarging electric power Wout of the electric power storage device 40(Step S450).

Subsequently, the HVECU 70 determines whether or not to permit theexecution of the catalyst temperature increase control routine, that is,the stop of the fuel supply to a part of cylinders 11 (hereinafter, “thestop of the fuel supply” is appropriately referred to as “fuel cut(F/C)”) according to a request from the engine ECU 100 (Step S460). InStep S460, the HVECU 70 calculates drive torque that is insufficient dueto fuel cut of one cylinder 11, that is, torque (hereinafter,appropriately referred to as “insufficient torque”) that is not outputfrom the engine 10 due to the fuel cut. In more detail, the HVECU 70calculates insufficient torque (=Tr*·G/n) by multiplying a valueobtained by dividing the requested torque Tr* set in Step S410 by thenumber n of cylinders (in the embodiment, n=4) of the engine 10 by agear ratio G between the rotor of the motor generator MG2 and the driveshaft DS. In Step S460, the HVECU 70 determines whether or not theinsufficient torque can be supplemented by the motor generator MG2 basedon the insufficient torque, the torque commands Tm1*, Tm2* set in StepS450, and the allowable charging electric power Win and the allowabledischarging electric power Wout of the electric power storage device 40.In this case, in a case where the F/C cylinder addition request signalor the F/C cylinder reduction signal is received from the engine ECU100, the HVECU 70 determines a possibility of supplement of theinsufficient torque in view of an increase or a decrease in the numberof fuel cut cylinders.

As a result of the determination processing of Step S460, in a casewhere determination is made that insufficient drive torque due to thefuel cut of a part (one or two) of cylinders 11 can be supplemented fromthe motor generator MG2 (Step S470: YES), the HVECU 70 transmits a fuelcut permission signal to the engine ECU 100 (Step S480). The fuel cutpermission signal also a fuel cut permission signal that permits solelyfuel cut of one cylinder 11 when the F/C cylinder addition requestsignal is transmitted from the engine ECU 100. As the result of thedetermination processing of Step S460, in a case where determination ismade that insufficient drive torque due to the fuel cut of a part ofcylinders 11 cannot be supplemented from the motor generator MG2 (StepS470: NO), the HVECU 70 transmits a fuel cut prohibition signal to theengine ECU 100 (Step S485), and ends the routine of FIGS. 6A and 6Bonce. In this case, the execution of the catalyst temperature increasecontrol routine by the engine ECU 100 is suspended or stopped.

In a case where the fuel cut permission signal is transmitted to theengine ECU 100 in Step S480, the HVECU 70 transmits the requested powerPe* set in Step S410 and the target rotation speed Ne* set in Step S440to the engine ECU 100 (Step S490). The HVECU 70 discriminates thecylinder 11, the fuel injection start timing of which is next reached,based on the crank position of the crank angle sensor 90 (Step S500). Ina case where determination is made through the discrimination processingof Step S500 that the fuel injection start timing of the fuel cutcylinder (the first cylinder #1 or the first cylinder #1 and the fourthcylinder #4) is reached (Step S510: NO), the HVECU 70 resets the torquecommand Tm2* to the motor generator MG2 (Step S515).

In Step S515, the HVECU 70 sets a sum of the torque command Tm2* set inStep S450 and the insufficient torque (=Tr*·G/n) as a new torque commandTm2*. After the processing of Step S515, the HVECU 70 transmits thetorque command Tm1* in Step S450 and the torque command Tm2* reset inStep S515 to the MGECU 55 (Step S560), and ends the routine of FIGS. 6Aand 6B once. With this, while the fuel supply to one cylinder 11 of theengine 10 is stopped (during fuel cut), control is executed by the MGECU55 such that the motor generator MG1 rotates the engine 10 at the targetrotation speed Ne*, and control is executed by the MGECU 55 such thatthe motor generator MG2 supplements the insufficient torque.

In contrast, in a case where determination is made through thediscrimination processing of Step S500 that the fuel injection starttiming of each of the combustion cylinders (the second cylinder #2 tothe fourth cylinder #4 or the second cylinder #2 and the third cylinder#30068) is reached (Step S510: YES), the HVECU 70 determines whether ornot the richness flag Fr acquired in Step S400 is the value 1 (StepS520). In a case where determination is made in Step S520 that therichness flag Fr is the value 1 (Step S520: YES), the HVECU 70calculates excess torque Tex (positive value) of the engine 10 thatoccurs the richness of the air-fuel ratio in one combustion cylinderfrom the accelerator operation amount Acc or the target torque Te* andan increase rate (in the embodiment, 20%) of fuel in one combustioncylinder used in Step S230 of FIG. 4 (Step S530).

The HVECU 70 determines whether or not the electric power storage device40 can be charged with electric power generated by the motor generatorMG1 based on the excess torque Tex, the target rotation speed Ne* andthe target torque Te* set in Step S440, the torque command Tm1* set inStep S450, and the allowable charging electric power Win of the electricpower storage device 40, and the like in a case where the excess torqueTex is cancelled while the engine 10 is rotated at the target rotationspeed Ne* by the motor generator MG1 (Step S540). In a case wheredetermination is made in Step S540 that the excess torque Tex can becancelled by the motor generator MG1 (Step S540: YES), the HVECU 70resets the torque commands Tm1*, Tm2* in view of the excess torque Tex(Step S550).

In Step S550, the HVECU 70 adds a value (negative value) of a componentin the excess torque Tex, which is applied to the motor generator MG1through the planetary gear 30, to the torque command Tm1* set in StepS450 to set a new torque command Tm1*. In Step S550, the HVECU 70subtracts a value (positive value) in the excess torque Tex, which istransmitted to the drive shaft DS through the planetary gear 30, fromthe torque command Tm2* to set a new torque command Tm2*. After theprocessing of Step S550, the HVECU 70 transmits the reset torquecommands Tm1*, Tm2* to the MGECU 55 (Step S560), and ends the routine ofFIGS. 6A and 6B once. With this, in a case where the excess torque Texcan be cancelled by the motor generator MG1, while fuel is supplied suchthat the air-fuel ratio in each of all combustion cylinders other thanthe fuel cut cylinder is made rich in Steps S230 to S270 of FIG. 4 ,control is executed by the MGECU 55 such that the motor generator MG1rotates the engine 10 at the target rotation speed Ne* and convertssurplus power of the engine 10 based on the excess torque Tex intoelectric power. In the interim, control is executed by the MGECU 55 suchthat the motor generator MG2 outputs torque according to the torquecommand Tm2* set in Step S450 without supplementing the insufficienttorque.

On the other hand, in a case where determination is made in Step S540that the excess torque Tex cannot be cancelled by the motor generatorMG1 (Step S540: YES), the HVECU 70 transmits an ignition retard requestsignal for requesting retard of an ignition timing to the engine ECU 100(Step S555). The HVECU 70 transmits the torque commands Tm1*, Tm2* setin Step S450 to the MGECU 55 (Step S560), and ends the routine of FIGS.6A and 6B once. With this, in a case where the excess torque Tex cannotbe cancelled by the motor generator MG1, while fuel is supplied suchthat the air-fuel ratio in each of all combustion cylinders other thanthe fuel cut cylinder is made rich in Steps S230 to S270 of FIG. 4 ,control is executed by the MGECU 55 such that the motor generator MG1rotates the engine 10 at the target rotation speed Ne*. In the interim,control is executed by the MGECU 55 such that the motor generator MG2outputs torque according to the torque command Tm2* set in Step S450without supplementing the insufficient torque. In a case where theignition retard request signal from the HVECU 70 is received, as shownin FIG. 7 , the engine ECU 100 retards the ignition timing in each ofthe combustion cylinders from an optimum ignition timing (MBT) such thatthe output torque of the engine 10 becomes the same as in a case wherethe air-fuel ratio in each of the combustion cylinders is set to astoichiometric air-fuel ratio.

In a case where determination is made in Step S520 that the richnessflag Fr is the value 0 (Step S520: NO), the HVECU 70 transmits thetorque commands Tm1*, Tm2* set in Step S450 to the MGECU 55 (Step S550),and ends the routine of FIGS. 6A and 6B once. With this, while therichness flag Fr is the value 0, and fuel is supplied such that theair-fuel ratio in each of all combustion cylinders other than the fuelcut cylinder becomes a value (slightly rich) on the lean side in StepsS310 and S240 to S270 of FIG. 4 , control is executed by the MGECU 55that the motor generator MG1 rotates the engine 10 at the targetrotation speed Ne*. In the meantime, control is executed by the MGECU 55such that the motor generator MG2 outputs torque according to the torquecommand Tm2* set in Step S450 without supplementing the insufficienttorque.

As a result of the execution of the routines of FIGS. 3 to 6A and 6Bdescribed above, in the hybrid vehicle 1, in a case where the depositionamount Dpm of the particulate matters in the particulate filter 190 ofthe downstream control apparatus 19 becomes equal to or greater than thethreshold value D1, the catalyst temperature increase request signal istransmitted from the engine ECU 100 to the HVECU 70 in order to increasethe temperature of the exhaust gas removing catalyst 180 of the upstreamcontrol apparatus 18 and the temperature of the particulate filter 190of the downstream control apparatus 19 (Step S150 of FIG. 3 ). Then, ina case where the temperature increase of the particulate filter 190 andthe like is permitted by the HVECU 70, while the engine 10 is in theload operation according to the depression amount of the acceleratorpedal 84 by the driver, the engine ECU 100 executes the catalysttemperature increase control routine (FIGS. 4 and 5 ) for stopping thefuel supply to at least one cylinder 11 of the engine 10 and supplyingfuel to the remaining cylinders 11. During the execution of the catalysttemperature increase control routine, the HVECU 70 executes control suchthat the motor generator MG2 as a power generation device supplementsinsufficient torque (drive power) due to the stop of the fuel supply toat least one cylinder 11 (FIGS. 6A and 6B).

With this, it is possible to supplement insufficient torque due to thestop of the fuel supply to a part of cylinders 11 from the motorgenerator MG2 with high accuracy and excellent responsiveness, and tooutput torque according to the requested torque Tr* to the wheels Wduring the execution of the catalyst temperature increase controlroutine. The HVECU 70 (and the MGECU 55) executes control such that themotor generator MG2 (electric motor) supplements insufficient torquewhile the fuel supply to at least one cylinder 11 is stopped (duringfuel cut) (Steps S515 and S560 of FIG. 6B). With this, it is possible toextremely satisfactorily suppress deterioration of drivability of thehybrid vehicle 1 during the execution of the catalyst temperatureincrease control routine.

During the execution of the catalyst temperature increase controlroutine, the HVECU 70 sets the lower limit rotation speed Nelim of theengine 10 to be higher than in a case where the catalyst temperatureincrease control routine is not executed (Step S430 of FIG. 6A). Withthis, it is possible to reduce a time for which the fuel supply to apart of cylinders 11 is stopped, that is, a time for which torque is notoutput from the engine 10 due to the fuel cut. Accordingly, in thehybrid vehicle 1, it is possible to extremely satisfactorily suppressactualization of vibration or the like of the engine 10 due to the fuelcut of a part of cylinders 11.

In a case where the execution of the catalyst temperature increasecontrol routine is permitted by the HVECU 70 (time t1 in FIG. 8 ), theengine ECU 100 stops the fuel supply to one cylinder 11 (first cylinder#1) of the engine 10, and makes the air-fuel ratio in each of theremaining cylinders 11 (the second cylinder #2, the third cylinder #3,and the fourth cylinder #4) rich (Steps S230 to S270 of FIG. 4 ). Withthis, a comparatively large amount of air, that is, oxygen is introducedfrom the cylinder 11 (fuel cut cylinder), to which the fuel supply isstopped, into the upstream and downstream control apparatuses 18, 19,and a comparatively large amount of unburned fuel is introduced from thecylinders 11 (combustion cylinders), to which fuel is supplied, into theupstream and downstream control apparatuses 18, 19. That is, thesubstantially same amount of air (not gas in a lean atmosphere, but airrarely including a fuel component) as the capacity (volume) of thecylinder 11 is supplied from the fuel cut cylinder to the upstream anddownstream control apparatuses 18, 19. As a result, a comparativelylarge amount of unburned fuel is brought into reaction in presence of asufficient amount of oxygen during the load operation of the engine 10,and as shown in FIG. 8 , it is possible to sufficiently and quickly thetemperature of the exhaust gas removing catalyst 180 or the particulatefilter 190, on which the exhaust gas removing catalyst is carried, withreaction heat.

While fuel is supplied such that the air-fuel ratio in each of allcombustion cylinders other than the fuel cut cylinder is made rich inthis way, the HVECU 70 (and the MGECU 55) executes control such that themotor generator MG1 (second electric motor) converts surplus power ofthe engine 10 generated by richness of the air-fuel ratio in each of theremaining cylinders 11 (combustion cylinders) into electric power (StepsS510 to S560 of FIG. 6B). With this, it is possible to suppressdeterioration of fuel efficiency of the engine 10 accompanied by theexecution of the catalyst temperature increase control routine withoutcomplicating the control of the motor generator MG2 for supplementingthe insufficient torque.

In a case where charging of the electric power storage device 40 isrestricted, and the surplus power of the engine 10 cannot be convertedinto electric power by the motor generator MG1, the HVECU 70 transmitsthe ignition retard request signal for requesting the retard of theignition timing to the engine ECU 100 (Step S555 of FIG. 6B). Then, theengine ECU 100 that receives the ignition retard request signal retardsthe ignition timing in each of the combustion cylinders from the optimumignition timing (MBT). With this, even though charging of the electricpower storage device 40 with electric power generated by the motorgenerator MG1 is restricted, it is possible to suppress an increase inoutput torque of the engine 10 accompanied by richness of the air-fuelratio in each of the combustion cylinders to satisfactorily securedrivability of the hybrid vehicle 1.

The engine ECU 100 changes the air-fuel ratio in each of all remainingcylinders 11 (combustion cylinders) to the lean side to make theair-fuel ratio slightly rich while stopping the fuel supply to the onecylinder 11 (the first cylinder #1) after the temperature Tpf of theparticulate filter 190 becomes equal to or higher than the regenerativetemperature Ty (first determination threshold value) (time t2 in FIG. 8) during the execution of the catalyst temperature increase control(Step S310 of FIG. 5 , or the like). The engine ECU 100 stops the fuelsupply to one (the fourth cylinder #4) of the remaining cylinders 11under a condition that insufficient torque due to the execution of thecatalyst temperature increase control routine can be supplemented by themotor generator MG2 (Steps S460 to S480 of FIG. 6A) after thetemperature Tpf of the particulate filter 190 becomes equal to or higherthan the regeneration promotion temperature Tz (second determinationthreshold value) higher than the regenerative temperature Ty (time t3 inFIG. 8 ) during the execution of the catalyst temperature increasecontrol (Step S305 of FIG. 5 , or the like).

With this, it is possible to supply a greater amount of oxygen from aplurality of fuel cut cylinders into the upstream and downstream controlapparatuses 18, 19, which are sufficiently increased in temperature,while stably operating the engine 10, in which the fuel supply to a partof cylinders 11 is stopped. Accordingly, in the hybrid vehicle 1, it ispossible to introduce a greater amount of oxygen from the fuel cutcylinders into the particulate filter 190, which is increased intemperature along with the exhaust gas removing catalyst, tosatisfactorily combust the particulate matters deposited on theparticulate filter 190. In the hybrid vehicle 1, it is also possible tosatisfactorily reduce S poisoning or HC poisoning of the exhaust gasremoving catalyst 180 of the upstream control apparatus 18.

In a case where the addition of the fuel cut cylinder is permitted bythe HVECU 70, the engine ECU 100 selects, as a new fuel cut cylinder,the cylinder 11 (the fourth cylinder #4) to which the fuel injection(ignition) is not executed successively with respect to the one cylinder11 (the first cylinder #1) when the catalyst temperature increasecontrol routine is not executed. That is, in a case where fuel supply totwo (a plurality of) cylinders 11 should be stopped, the engine ECU 100executes the catalyst temperature increase control routine such thatfuel is supplied to at least one cylinder 11 after the fuel supply toone cylinder 11 is stopped. With this, since the fuel supply to aplurality of cylinders 11 is not stopped successively, it is possible tosuppress fluctuation of torque or deterioration of engine sound outputfrom the engine 10.

In a case where the temperature Tpf of the particulate filter 190becomes lower than the temperature increase control start temperature Txafter the fuel cut cylinder is added (time t4 in FIG. 8 ), as shown inFIG. 8 , the engine ECU 100 decreases the number of fuel cut cylindersand makes the air-fuel ratio in each of the cylinders 11 (combustioncylinders), to which fuel is supplied, rich (Step S325 of FIG. 5 , andSteps S220 to S270 of FIG. 4 ). With this, in a case where both of theupstream and downstream control apparatuses 18, 19 are reduced intemperature according to an increase in air introduction amount into theupstream and downstream control apparatuses 18, 19 accompanied by theaddition of the fuel cut cylinder, it is possible to make the air-fuelratio in each of the combustion cylinders rich to increase thetemperatures of the upstream and downstream control apparatuses 18, 19again, and to decrease the amount of air introduced into the upstreamand downstream control apparatuses 18, 19 with a decrease in the numberof fuel cut cylinders to suppress a temperature reduction of both of theupstream and downstream control apparatuses 18, 19.

Then, in a case where the deposition amount Dpm in the particulatefilter 190 becomes equal to or less than the threshold value D0 (time t5in FIG. 8 ), the engine ECU 100 turns off the catalyst temperatureincrease flag and ends the catalyst temperature increase controlroutine. Note that, in a case where a duration of an accelerator ONstate is comparatively short, and in the interim, the deposition amountDpm in the particulate filter 190 does not become equal to or less thanthe threshold value D0, the routines of FIGS. 4 to 6A and 6B areinterrupted, and are restarted when the accelerator pedal 84 is nextdepressed by the driver.

As described above, in the hybrid vehicle 1, it is possible tosufficiently and quickly increase the temperatures of the upstream anddownstream control apparatuses 18, 19 and to supply a sufficient amountof oxygen for the generation of the exhaust gas removing catalyst 180 orthe particulate filter 190 to the upstream and downstream controlapparatuses 18, 19 while suppressing deterioration of drivability duringthe load operation of the engine 10. That is, with the above-describedcatalyst temperature increase control routine, even in a low-temperatureenvironment that a large amount of particulate matters tends to bedeposited on the particulate filter 190, in particular, even in anextremely low-temperature environment that a daily average airtemperature falls below −20° C., it is possible to satisfactorilycombust the particulate matters deposited on the particulate filter 190to regenerate the particulate filter 190.

In the above-described embodiment, although the air-fuel ratio in eachof all combustion cylinders other than the fuel cut cylinder is maderich in a case where the execution of the catalyst temperature increasecontrol routine is permitted, an applicable embodiment of the presentdisclosure is not limited thereto. That is, in the hybrid vehicle 1, theengine ECU 100 may set the air-fuel ratio in each of the combustioncylinders to the stoichiometric air-fuel ratio instead of making theair-fuel ratio in each of the combustion cylinders rich at the beginningof the start of the catalyst temperature increase control routine. Insuch an aspect, while a time is needed for increasing the temperaturesof the upstream and downstream control apparatuses 18, 19 compared to acase where the air-fuel ratio in each of the combustion cylinders ismade rich, it is possible to bring unburned fuel into reaction inpresence of a sufficient amount of oxygen to sufficiently increase thetemperatures of the upstream and downstream control apparatuses 18, 19with reaction heat. The fuel supply to a part of cylinders 11 is stoppedsuccessively, whereby it is possible to supply a sufficient amount ofoxygen into the upstream and downstream control apparatuses 18, 19,which are increased in temperature.

In the above-described embodiment, although the air-fuel ratio in eachof all combustion cylinders is changed to the lean side after thetemperature Tpf of the particulate filter 190 becomes equal to or higherthan the regenerative temperature Ty (first determination thresholdvalue), an applicable embodiment of the present disclosure is notlimited thereto. That is, in the hybrid vehicle 1, the air-fuel ratio ineach of the remaining cylinders 11 other than the fuel cut cylinder maybe made rich until the temperature Tpf of the particulate filter 190reaches the regeneration promotion temperature Tz (determinationthreshold value). Then, the fuel supply to one of the remainingcylinders 11 may be stopped and the air-fuel ratio in the cylinder 11,to which the fuel supply is not stopped, among the remaining cylinders11 may be changed to lean side (slightly rich) under a condition thatthe insufficient torque can be supplemented by the motor generator MG2after the temperature Tpf becomes equal to or higher than theregeneration promotion temperature Tz. According to such an aspect, itis possible to supply a greater amount of oxygen into the upstream anddownstream control apparatuses 18, 19 after sufficiently and quicklyincreasing the temperature of the exhaust gas removing catalyst 180 orthe particulate filter 190.

In Step S310 of FIG. 5 , the fuel injection amount may be set such thatthe air-fuel ratio in each of all combustion cylinders other than thefuel cut cylinder is made lean. After the temperature Tpf of theparticulate filter 190 becomes equal to or higher than the regenerationpromotion temperature Tz, as indicated by a two-dot-chain line in FIG. 8, the engine ECU 100 may make the air-fuel ratio in each of allcombustion cylinders other than the fuel cut cylinder lean instead ofadding a fuel cut cylinder. When the air-fuel ratio in each of thecombustion cylinder should be changed during the execution of thecatalyst temperature increase control routine, as indicated by a brokenline in FIG. 8 , for example, the air-fuel ratio in each of thecombustion cylinder may be gradually changed according to change in thetemperature Tpf of the particulate filter 190, or the like.

In the hybrid vehicle 1, the surplus power of the engine 10 generated byrichness of the air-fuel ratio in each of the combustion cylinders maybe converted into electric power by the motor generator MG2 instead ofthe motor generator MG1. In this case, in Step S540 of FIG. 6B,determination is made whether or not the electric power storage device40 can be charged with electric power generated by the motor generatorMG2 in a case where the excess torque Tex is cancelled by the motorgenerator MG2. In Step S550 of FIG. 6B, torque corresponding to theexcess torque Tex is subtracted from the torque command Tm2* set in StepS450 to reset the torque command Tm2*. Then, in Step S560, the torquecommand Tm1* set in Step S450 and the torque command Tm2* reset in theStep S550 are transmitted to the MGECU 55. Then, in a case wheredetermination is made in Step S520 of FIG. 6B that the richness flag Fris the value 1, the ignition retard request signal may be transmitted tothe engine ECU 100. With the aspects, when the air-fuel ratio in each ofthe combustion cylinder is made rich during the execution of thecatalyst temperature increase control routine, it is possible to outputtorque according to the requested torque Tr* to the wheels W tosatisfactorily secure drivability of the hybrid vehicle 1.

Although the engine 10 of the hybrid vehicle 1 is an in-line engine, andthe catalyst temperature increase control routine is constructed to stopthe fuel supply to at least one cylinder 11 is stopped during one cycle,an applicable embodiment of the present disclosure is not limitedthereto. That is, the engine 10 of the hybrid vehicle 1 may be aV-shaped engine, a horizontal opposed engine, or a W-shaped engine inwhich an exhaust gas control apparatus is provided for each bank. Inthis case, the catalyst temperature increase control routine may beconstructed such that fuel supply to at least one cylinder in each bankis stopped during one cycle. With this, it is possible to send asufficient amount of oxygen to the exhaust gas control apparatus in eachbank of the V-shaped engine or the like.

The downstream control apparatus 19 may include an exhaust gas removingcatalyst (three-way catalyst) disposed on an upstream side, and aparticulate filter disposed downstream of the exhaust gas removingcatalyst. In this case, the hybrid vehicle 1 to the upstream controlapparatus 18 may be omitted. The downstream control apparatus 19 mayinclude solely the particulate filter. In this case, the exhaust gasremoving catalyst of the upstream control apparatus 18 is increased intemperature with the execution of the catalyst temperature increasecontrol routine, whereby it is possible to increase the temperature ofthe downstream control apparatus 19 (the particulate filter 190) withhigh-temperature exhaust gas flowing from the upstream control apparatus18.

In the hybrid vehicle 1, the motor generator MG1 may be coupled to thesun gear 31 of the planetary gear 30, the output member may be coupledto the ring gear 32, and the engine 10 and the motor generator MG2 maybe coupled to the planetary carrier 34. A stepped transmission may becoupled to the ring gear 32 of the planetary gear 30. In the hybridvehicle 1, the planetary gear 30 may be replaced with a four-elementcompound planetary gear mechanism including two planetary gears. In thiscase, the engine 10 may be coupled to an input element of the compoundplanetary gear mechanism, the output member may be coupled to an outputelement, the motor generator MG1 may be coupled to one of remaining tworotating elements, and the motor generator MG2 may be coupled to theother rotating element. The compound planetary gear mechanism may beprovided with a clutch that couples two of the four rotating elements ora brake that can unrotatably fix one rotating element. The hybridvehicle 1 may be constituted as a plug-in hybrid vehicle that can chargethe electric power storage device 40 with electric power from anexternal power supply, such as a household power supply or a rapidcharger provided in a stand.

FIG. 9 is a schematic configuration diagram showing another hybridvehicle 1B of the present disclosure. Among the components of the hybridvehicle 1B, the same components as those of the hybrid vehicle 1described above are represented by the same reference numerals, andoverlapping description will not be repeated.

The hybrid vehicle 1B shown in FIG. 9 is a series-parallel hybridvehicle including an engine (internal combustion engine) 10B including aplurality of cylinders (not shown), motor generators (synchronous motorgenerators) MG1, MG2, and a transaxle 20B. The engine 10B includes anupstream control apparatus 18 and a downstream control apparatus 19 asan exhaust gas control apparatus. A crankshaft (not shown) of the engine10B, a rotor of the motor generator MG1, and wheels W1 are coupled to atransaxle 20B. The motor generator MG2 is coupled to wheels W2 differentto the wheels W1. Note that the motor generator MG2 may be coupled tothe wheels W1. The transaxle 20B may include a stepped transmission, acontinuously variable transmission, a dual-clutch transmission, or thelike.

The hybrid vehicle 1B can travel with drive torque (drive power) from atleast one of the motor generators MG1, MG2 that are driven with electricpower from the electric power storage device 40 when the operation ofthe engine 10B is stopped. In the hybrid vehicle 1B, the whole powerfrom the engine 10B in the load operation can be converted into electricpower by the motor generator MG1, and the motor generator MG2 can bedriven with electric power from the motor generator MG1. In the hybridvehicle 1B, drive torque (drive power) from the engine 10B in the loadoperation can be transmitted to the wheels W1 through the transaxle 20B.

In the hybrid vehicle 1B, while the drive torque from the engine 10B inthe load operation is transmitted to the wheels W1 through the transaxle20B, the same catalyst temperature increase control routine as shown inFIGS. 4 and 5 is executed by the engine ECU (not shown). While thecatalyst temperature increase control routine is executed, control isexecuted such that the motor generator MG2 supplements insufficientdrive torque due to the fuel cut of a part of cylinders of the engine10B. With this, in the hybrid vehicle 1B, it is possible to obtain thesame advantageous effects as the hybrid vehicle 1. In the hybrid vehicle1B, during the execution of the catalyst temperature increase controlroutine, a down-shift (change of a gear ratio) of a transmissionincluded in the transaxle 20B may be appropriately executed to make therotation speed of the engine 10B be equal to or higher than apredetermined rotation speed. With this, it is possible to increase therotation speed of the engine 10B to reduce a time for which the fuelsupply to a part of cylinders is stopped, and to extremelysatisfactorily suppress actualization of vibration of the like of theengine 10B.

FIG. 10 is a schematic configuration diagram showing still anotherhybrid vehicle 1C of the present disclosure. Among the components of thehybrid vehicle 1C, the same components as those of the hybrid vehicle 1and the like described above are represented by the same referencenumerals, and overlapping description will not be repeated.

The hybrid vehicle 1C shown in FIG. 10 is a series-parallel hybridvehicle including an engine (internal combustion engine) 10C including aplurality of cylinders (not shown), and motor generators (synchronousmotor generators) MG1, MG2. In the hybrid vehicle 1C, a crankshaft ofthe engine 10C and a rotor of the motor generator MG1 are coupled to afirst shaft S1, and the motor generator MG1 can convert at least a partof power from the engine 10C into electric power. A rotor of the motorgenerator MG2 is coupled to a second shaft S2 directly or through apower transmission mechanism 120 including a gear train and the like,and the second shaft S2 is coupled to the wheels W through thedifferential gear 39 and the like. Note that the motor generator MG2 maybe coupled to wheels (not shown) other than the wheels W. The hybridvehicle 1C includes a clutch K that connects the first shaft S1 and thesecond shaft S2 to each other and disconnects both shafts. In the hybridvehicle 1C, the power transmission mechanism 120, the clutch K, and thedifferential gear 39 may be included in a transaxle.

In the hybrid vehicle 1C, it is possible to output drive torque from theengine 10C to the second shaft S2, that is, the wheels W when the clutchK is engaged. Then, in the hybrid vehicle 1C, while the crankshaft ofthe engine 10C and the second shaft S2, that is, the wheels W arecoupled by the clutch K, and the engine 10C is in the load operationaccording to depression of the accelerator pedal by the driver, the samecatalyst temperature increase control routine as shown in FIGS. 4 and 5is executed by the engine ECU (not shown). While the catalysttemperature increase control routine is executed, control is executedsuch that the motor generator MG2 supplements insufficient drive torquedue to the fuel cut of a part of cylinders of the engine 10C. With this,in the hybrid vehicle 1C, it is possible to obtain the same advantageouseffects as the hybrid vehicle 1 and the like.

FIG. 11 is a schematic configuration diagram showing still anotherhybrid vehicle 1D of the present disclosure. Among the components of thehybrid vehicle 1D, the same components as those of the hybrid vehicle 1and the like described above are represented by the same referencenumerals, and overlapping description will not be repeated.

The hybrid vehicle 1D shown in FIG. 11 is a parallel hybrid vehicleincluding an engine (internal combustion engine) 10D including aplurality of cylinders (not shown), a motor generator (synchronous motorgenerator) MG, a hydraulic clutch K0, a power transmission device 21, anelectric power storage device (high-voltage battery) 40D, an accessorybattery (low-voltage battery) 41, a PCU 50D that drives the motorgenerator MG, an MGECU 55D that controls the PCU 50D, and a mainelectronic control unit (hereinafter, referred to as “main ECU”) 170that controls the engine 10D and the power transmission device 21. Theengine 10D includes an upstream control apparatus 18 and a downstreamcontrol apparatus 19 as an exhaust gas control apparatus, and acrankshaft of the engine 10D is coupled to an input member of a dampermechanism 24. The motor generator MG operates as an electric motor thatis driven with electric power from the electric power storage device 40Dto generate drive torque, and outputs regenerative braking torque at thetime of braking of the hybrid vehicle 1D. The motor generator MG alsooperates a power generator that converts at least a part of power fromthe engine 10D in a load operation into electric power. As shown in thedrawing, a rotor of the motor generator MG is fixed to an input shaft 21i of the power transmission device 21.

The clutch K0 couples an output member of the damper mechanism 24, thatis, the crankshaft of the engine 10D and the input shaft 21 i, that is,the rotor of the motor generator MG, and decouples both of the outputmember of the damper mechanism 24 and the input shaft 21 i. The powertransmission device 21 includes a torque converter (fluid-operated powertransmission device) 22, a multi-plate or single-plate lockup clutch 23,a mechanical oil pump MOP, an electric oil pump EOP, a transmission 25,a hydraulic control device 27 that controls pressure of hydraulic oil,and the like. The transmission 25 is, for example, a four-speed toten-speed gear shift type automatic transmission, and includes aplurality of planetary gear and a plurality of clutches and brakes(frictional engagement elements). The transmission 25 outputs powertransmitted from the input shaft 21 i through either of the torqueconverter 22 or the lockup clutch 23 from an output shaft 210 of thepower transmission device 21 to a drive shaft DS through thedifferential gear 39 with a gear shift in a plurality of stages. Notethat the transmission 25 may be a mechanical continuously variabletransmission, a dual-clutch transmission, or the like. A clutch may bedisposed between the rotor of the motor generator MG and the input shaft21 i of the power transmission device 21 to couple or decouple both ofrotor of the motor generator MG and the input shaft 21 i of the powertransmission device 21 (see a two-dot-chain line in FIG. 11 ).

In the hybrid vehicle 1D, while the crankshaft of the engine 10D and theinput shaft 21 i, that is, the motor generator MG are coupled by theclutch K0, and the engine 10D is in the load operation according todepression of the accelerator pedal by the driver, the same catalysttemperature increase control routine as shown in FIGS. 4 and 5 isexecuted by the main ECU 170. While the catalyst temperature increasecontrol routine is executed, the main ECU 170 and the MGECU 55D executecontrol such that the motor generator MG supplements insufficient drivetorque due to the fuel cut of a part of cylinders of the engine 10D.With this, in the hybrid vehicle 1D, it is possible to obtain the sameadvantageous effects as the hybrid vehicle 1 and the like. In the hybridvehicle 1D, when the air-fuel ratio in each of the combustion cylindersis made rich, surplus power of the engine 10D may be converted intoelectric power by the motor generator MG, or an increase in outputtorque of the engine 10D may be suppressed by the retard of the ignitiontiming. In the hybrid vehicle 1D, during the execution of the catalysttemperature increase control routine, a down-shift (change of a gearratio) of the transmission 25 may be appropriately executed to make therotation speed of the engine 10D be equal to or higher than apredetermined rotation speed.

FIG. 12 is a schematic configuration diagram showing still anotherhybrid vehicle 1E of the present disclosure. Among the components of thehybrid vehicle 1E, the same components as those of the hybrid vehicle 1and the like described above are represented by the same referencenumerals, and overlapping description will not be repeated.

The hybrid vehicle 1E shown in FIG. 12 includes an engine (internalcombustion engine) 10E including a plurality of cylinders (not shown), amotor generator (synchronous motor generator) MG, a power transmissiondevice 21E, a high-voltage battery 40E, a low-voltage battery (accessorybattery) 41E, a DC/DC converter 44 connected to the high-voltage battery40E and the low-voltage battery 41E, an inverter 54 that drives themotor generator MG, an engine ECU 100E that controls the engine 10E, anMGECU 55E that controls the DC/DC converter 44 and the inverter 54, andan HVECU 70E that controls the entire vehicle. The engine 10E includesan upstream control apparatus 18 and a downstream control apparatus 19as an exhaust gas control apparatus, and a crankshaft 12 of the engine10E is coupled to an input member of a damper mechanism (not shown)included in the power transmission device 21E. The engine 10E includes astarter 130 that output cranking torque to the crankshaft 12 to startthe engine 10E.

A rotor of the motor generator MG is coupled to an end portion of thecrankshaft 12 of the engine 10E on an opposite side to the powertransmission device 21E through a power transmission mechanism 140. Inthe embodiment, the power transmission mechanism 140 is a winding powertransmission mechanism, a gear mechanism, or a chain mechanism. Notethat the motor generator MG may be disposed between the engine 10E andthe power transmission device 21E or may be a direct-current electricmotor. The power transmission device 21E includes, in addition to thedamper mechanism, a torque converter (fluid-operated power transmissiondevice), a multi-plate or single-plate lockup clutch, a transmission, ahydraulic control device that controls pressure of hydraulic oil, andthe like. The transmission of the power transmission device 21E is astepped transmission, a mechanical continuously variable transmission, adual-clutch transmission, or the like.

In the hybrid vehicle 1E, cranking torque is output from the motorgenerator MG to the crankshaft 12 through the power transmissionmechanism 140, whereby the engine 10E can be started. During travelingof the hybrid vehicle 1E, the motor generator MG primarily operates as apower generator that converts a part of power from the engine 10E in theload operation into electric power, and is appropriately driven withelectric power from the high-voltage battery 40E to output drive torque(assist torque) to the crankshaft 12 of the engine 10E. At the time ofbraking of the hybrid vehicle 1E, the motor generator MG outputsregenerative braking torque to the crankshaft 12 of the engine 10E.

In the hybrid vehicle 1E, while the engine 10E is in the load operationaccording to depression of the accelerator pedal by the driver, the samecatalyst temperature increase control routine as shown in FIGS. 4 and 5is executed by the engine ECU 100E. While the catalyst temperatureincrease control routine is executed, the HVECU 70E and the MGECU 55Eexecute control such that the motor generator MG supplementsinsufficient drive torque due to the fuel cut of a part of cylinders ofthe engine 10E. With this, in the hybrid vehicle 1E, it is possible toobtain the same advantageous effects as the hybrid vehicle 1 and thelike. In the hybrid vehicle 1E, when the air-fuel ratio in each of thecombustion cylinders is made rich, surplus power of the engine 10E maybe converted into electric power by the motor generator MG, or anincrease in the output torque of the engine 10E may be suppressed by theretard of the ignition timing. In the hybrid vehicle 1E, during theexecution of the catalyst temperature increase control routine, adown-shift (change of a gear ratio) of the transmission of the powertransmission device 21E may be appropriately executed to make therotation speed of the engine 10E be equal to or higher than apredetermined rotation speed.

As described above, the present disclosure provides a hybrid vehicle.The hybrid vehicle includes a multi-cylinder engine, an exhaust gascontrol apparatus, an electric motor, and an electric power storagedevice. The exhaust gas control apparatus includes a catalyst. Thecatalyst is configured to remove exhaust gas from the multi-cylinderengine. The electric power storage device is configured to exchangeelectric power with the electric motor. At least one of themulti-cylinder engine and the electric motor outputs drive power towheels. The hybrid vehicle further includes a control device. Thecontrol device is configured to execute catalyst temperature increasecontrol for stopping fuel supply to at least one cylinder and making anair-fuel ratio in each of remaining cylinders other than the at leastone cylinder rich in a case where a temperature increase of the catalystis requested during a load operation of the multi-cylinder engine,execute control such that the electric motor supplements insufficientdrive power due to the execution of the catalyst temperature increasecontrol, and change the air-fuel ratio in at least one of the remainingcylinders to a lean side after a temperature of the exhaust gas controlapparatus becomes equal to or higher than a determination thresholdvalue determined in advance during the execution of the catalysttemperature increase control.

The control device of the hybrid vehicle of the present disclosure isconfigured to execute the catalyst temperature increase controlmulti-cylinder engine for stopping the fuel supply to the at least onecylinder and making the air-fuel ratio in each of the remainingcylinders rich in a case where the temperature increase of the catalystis requested during the load operation of the multi-cylinder engine.With this, during the execution of the catalyst temperature increasecontrol, a comparatively large amount of air, that is, oxygen isintroduced from the cylinder, to which the fuel supply is stopped, intothe exhaust gas control apparatus, and a comparatively large amount ofunburned fuel is introduced from the cylinders, to which fuel issupplied, into the exhaust gas control apparatus. As a result, it ispossible to bring a comparatively large amount of unburned fuel intoreaction in presence of a sufficient amount of oxygen to sufficientlyand quickly the temperature of the catalyst with reaction heat duringthe load operation of the multi-cylinder engine. The control device isconfigured to change the air-fuel ratio in at least one of the remainingcylinders to the lean side while stopping the fuel supply to the atleast one cylinder in a case where the temperature of the exhaust gascontrol apparatus becomes equal to or higher than the determinationthreshold value determined in advance. With this, it is possible tosupply a large amount of oxygen into the exhaust gas control apparatus,which is increased in temperature. Then, the control device isconfigured to execute control such that the electric motor supplementsinsufficient drive power due to the catalyst temperature increasecontrol, that is, the stop of the fuel supply to the at least onecylinder during the execution of the catalyst temperature increasecontrol. With this, it is possible to supplement insufficient drivepower due to the stop of the fuel supply to a part of cylinders from theelectric motor with high accuracy and excellent responsiveness duringthe execution of the catalyst temperature increase control, and tooutput drive power according to the request to the wheels. Accordingly,in the hybrid vehicle of the present disclosure, it is possible tosufficiently and quickly increase the temperature of the catalyst of theexhaust gas control apparatus and to supply a sufficient amount ofoxygen to the exhaust gas control apparatus while suppressingdeterioration of drivability during the load operation of themulti-cylinder engine.

The control device may be configured to change the air-fuel ratio ineach of the remaining cylinders to a lean side after the temperature ofthe exhaust gas control apparatus becomes equal to or higher than afirst determination threshold value during the execution of the catalysttemperature increase control, and stop fuel supply to the at least oneof the remaining cylinders under a condition that the insufficient drivepower due to the execution of the catalyst temperature increase controlis able to be supplemented by the electric motor after the temperatureof the exhaust gas control apparatus becomes equal to or higher than asecond determination threshold value higher than the first determinationthreshold value. With this, it is possible to supply a greater amount ofoxygen into the exhaust gas control apparatus, which is sufficientlyincreased in temperature, while stably operating the multi-cylinderengine in which the fuel supply to a part of cylinders is stopped.

The control device may be configured to stop fuel supply to at least oneof the remaining cylinders and change the air-fuel ratio in each of thecylinders, to which the fuel supply is not stopped, among the remainingcylinders to a lean side under a condition that the insufficient drivepower due to the execution of the catalyst temperature increase controlis able to be supplemented by the electric motor after the temperatureof the exhaust gas control apparatus becomes equal to or higher than thedetermination threshold value during the execution of the catalysttemperature increase control. With this, it is possible to supply alarge amount of oxygen into the exhaust gas control apparatus aftersufficiently and quickly increasing the temperature of the catalyst.

The control device may be configured to make the air-fuel ratio in eachof the cylinders, to which fuel is supplied, rich in a case where thetemperature of the exhaust gas control apparatus becomes lower than apredetermined temperature after the air-fuel ratio in the at least oneof the remaining cylinders is changed to the lean side. With this, in acase where the temperature of the exhaust gas control apparatus isreduced with an increase in the amount of air introduced into theexhaust gas control apparatus, it is possible to make the air-fuel ratioin each of the cylinders, to which fuel is supplied, rich to increasethe temperature of the exhaust gas control apparatus again.

The control device may be configured to reduce the number of cylinders,to which the fuel supply is stopped, in a case where the temperature ofthe exhaust gas control apparatus becomes lower than the predeterminedtemperature after the air-fuel ratio in the at least one of theremaining cylinders is changed to the lean side. With this, it ispossible to decrease the amount of air introduced into the exhaust gascontrol apparatus to suppress a temperature reduction of the exhaust gascontrol apparatus.

The control device may be configured to execute the catalyst temperatureincrease control to supply fuel at least one cylinder after the fuelsupply to any one of the cylinders is stopped. With this, since the fuelsupply to a plurality of cylinders is not stopped successively, it ispossible to suppress fluctuation of torque output from themulti-cylinder engine or deterioration of engine sound.

The exhaust gas control apparatus may include a particulate filter. In avehicle that includes such an exhaust gas control apparatus, it ispossible to introduce a large amount of oxygen from the cylinder, towhich the fuel supply is stopped, into the particulate filter, which isincreased in temperature along with the catalyst to satisfactorilycombust the particulate matters deposited on the particulate filter.That is, the catalyst temperature increase control of the presentdisclosure is extremely useful in regenerating the particulate filter ina low-temperature environment that a large amount of particulate matterstends to be deposited on the particulate filter. Then, the particulatefilter may be disposed downstream of the catalyst or may carry thecatalyst. The exhaust gas control apparatus may include an upstreamcontrol apparatus that includes the catalyst, and a downstream controlapparatus that includes at least the particulate filter and is disposeddownstream of the upstream control apparatus.

The present disclosure also provides a control method for a hybridvehicle. The hybrid vehicle includes a multi-cylinder engine, an exhaustgas control apparatus, an electric motor, and an electric power storagedevice. The exhaust gas control apparatus includes a catalyst. Thecatalyst is configured to remove exhaust gas from the multi-cylinderengine. The electric power storage device is configured to exchangeelectric power with the electric motor. At least one of themulti-cylinder engine and the electric motor outputs drive power towheels. The control method includes executing catalyst temperatureincrease control for stopping fuel supply to at least one cylinder andmaking an air-fuel ratio in each of remaining cylinders other than theat least one cylinder rich in a case where a temperature increase of thecatalyst is requested during a load operation of the multi-cylinderengine, executing control such that the electric motor supplementsinsufficient drive power due to the execution of the catalysttemperature increase control, and changing the air-fuel ratio in atleast one of the remaining cylinders to a lean side after a temperatureof the exhaust gas control apparatus becomes equal to or higher than adetermination threshold value determined in advance during the executionof the catalyst temperature increase control.

With such a method, it is possible to sufficiently and quickly increasethe temperature of the catalyst of the exhaust gas control apparatus andto supply a sufficient amount of oxygen to the exhaust gas controlapparatus while suppressing deterioration of drivability during the loadoperation of the multi-cylinder engine.

An applicable embodiment of the present disclosure is not limited to theabove-described embodiment, and various alterations may be of coursemade within the scope of the extension of the present disclosure. Theabove-described embodiment is merely a specific form of the presentdisclosure described in SUMMARY, and does not limit the components ofthe present disclosure described in SUMMARY.

The present disclosure is usable in a manufacturing industry of a hybridvehicle, or the like.

What is claimed is:
 1. A hybrid vehicle comprising: a multi-cylinderengine; an exhaust gas control apparatus including a catalyst removingexhaust gas from the multi-cylinder engine; an electric motor; and anelectric power storage device configured to exchange electric power withthe electric motor, wherein: the hybrid vehicle is configured such thatat least one of the multi-cylinder engine and the electric motor outputsdrive power to wheels; and the hybrid vehicle further includes a controldevice configured to: execute catalyst temperature increase control forstopping fuel supply to at least one cylinder and making an air-fuelratio in each of remaining cylinders other than the at least onecylinder rich in a case where a temperature increase of the catalyst isrequested during a load operation of the multi-cylinder engine, executecontrol such that the electric motor supplements insufficient drivepower due to the execution of the catalyst temperature increase control,change the air-fuel ratio in at least one of the remaining cylinders toa lean side, which is higher than a stoichiometric air-fuel ratio, aftera temperature of the exhaust gas control apparatus becomes equal to orhigher than a determination threshold value determined in advance duringthe execution of the catalyst temperature increase control, and maintainthe air-fuel ratio at the stoichiometric air-fuel ratio prior to andafter the catalyst temperature increase control.
 2. The hybrid vehicleaccording to claim 1, wherein the control device is configured to changethe air-fuel ratio in each of the remaining cylinders to a lean sideafter the temperature of the exhaust gas control apparatus becomes equalto or higher than a first determination threshold value during theexecution of the catalyst temperature increase control, and stop fuelsupply to at least one of the remaining cylinders under a condition thatthe insufficient drive power due to the execution of the catalysttemperature increase control is able to be supplemented by the electricmotor after the temperature of the exhaust gas control apparatus becomesequal to or higher than a second determination threshold value higherthan the determination threshold value.
 3. The hybrid vehicle accordingto claim 1, wherein the control device is configured to stop fuel supplyto at least one of the remaining cylinders and change the air-fuel ratioin each of the cylinders, to which the fuel supply is not stopped, amongthe remaining cylinders to a lean side under a condition that theinsufficient drive power due to the execution of the catalysttemperature increase control is able to be supplemented by the electricmotor after the temperature of the exhaust gas control apparatus becomesequal to or higher than the determination threshold value during theexecution of the catalyst temperature increase control.
 4. The hybridvehicle according to claim 2, wherein the control device is configuredto make the air-fuel ratio in each of the cylinders, to which fuel issupplied, rich in a case where the temperature of the exhaust gascontrol apparatus becomes lower than the determination threshold afterthe air-fuel ratio in the at least one of the remaining cylinders ischanged to the lean side.
 5. The hybrid vehicle according to claim 4,wherein the control device is configured to reduce the number ofcylinders, to which the fuel supply is stopped, in a case where thetemperature of the exhaust gas control apparatus becomes lower than thedetermination threshold after the air-fuel ratio in the at least one ofthe remaining cylinders is changed to the lean side.
 6. The hybridvehicle according to claim 2, wherein the control device is configuredto execute the catalyst temperature increase control to supply fuel toat least one cylinder after the fuel supply to any one of the cylindersis stopped.
 7. The hybrid vehicle according to claim 1, wherein theexhaust gas control apparatus includes a particulate filter.
 8. Acontrol method for a hybrid vehicle, the hybrid vehicle including amulti-cylinder engine, an exhaust gas control apparatus including acatalyst for removing exhaust gas from the multi-cylinder engine, anelectric motor, and an electric power storage device configured toexchange electric power with the electric motor, and configured suchthat at least one of the multi-cylinder engine and the electric motoroutputs drive power to wheels, the control method comprising: executingcatalyst temperature increase control for stopping fuel supply to atleast one cylinder and making an air-fuel ratio in each of remainingcylinders other than the at least one cylinder rich in a case where atemperature increase of the catalyst is requested during a loadoperation of the multi-cylinder engine; executing control such that theelectric motor supplements insufficient drive power due to the executionof the catalyst temperature increase control; changing the air-fuelratio in at least one of the remaining cylinders to a lean side, whichis higher than a stoichiometric air-fuel ratio, after a temperature ofthe exhaust gas control apparatus becomes equal to or higher than adetermination threshold value determined in advance during the executionof the catalyst temperature increase control; and maintaining theair-fuel ratio at the stoichiometric air-fuel ratio prior to and afterthe catalyst temperature increase control.
 9. A hybrid vehiclecomprising: a multi-cylinder engine; an exhaust gas control apparatusincluding a catalyst removing exhaust gas from the multi-cylinderengine; an electric motor; and an electric power storage deviceconfigured to exchange electric power with the electric motor, wherein:the hybrid vehicle is configured such that at least one of themulti-cylinder engine and the electric motor outputs drive power towheels; and the hybrid vehicle further includes a control deviceconfigured to: execute catalyst temperature increase control forstopping fuel supply to at least one cylinder and making an air-fuelratio in each of remaining cylinders other than the at least onecylinder rich in a case when a catalyst temperature is below apredetermined temperature during a load operation of the multi-cylinderengine, execute control such that the electric motor supplementsinsufficient drive power due to the execution of the catalysttemperature increase control, change the air-fuel ratio in at least oneof the remaining cylinders to a lean side, which is higher than astoichiometric air-fuel ratio, after a temperature of the exhaust gascontrol apparatus becomes equal to or higher than the predeterminedtemperature during the execution of the catalyst temperature increasecontrol, and maintain the air-fuel ratio at the stoichiometric air-fuelratio prior to and after the catalyst temperature increase control. 10.The hybrid vehicle according to claim 9, wherein the at least onecylinder includes an intake valve and an exhaust valve, and controldevice is configured to execute the catalyst temperature increasecontrol by opening the intake valve and the exhaust valve during thestopping of the fuel supply to the at least one cylinder.
 11. The hybridvehicle according to claim 1, wherein the at least one cylinder includesan intake valve and an exhaust valve, and control device is configuredto execute the catalyst temperature increase control by opening theintake valve and the exhaust valve during the stopping of the fuelsupply to the at least one cylinder.
 12. The hybrid vehicle according toclaim 8, wherein the at least one cylinder includes an intake valve andan exhaust valve, and executing the catalyst temperature increasecontrol comprises opening the intake valve and the exhaust valve duringthe stopping of the fuel supply to the at least one cylinder.